How to change/edit existing URL

First of all, I apologize if this has been asked before. I tried searching for "edit/change link/URL" but come up empty. So here's my question:

Is there a way to edit existing link/URL? For example, if the existing link is dead and my download is incomplete, but I found another link to the exact same file in a resumable file sharing service e.g. BillionUpload, I can just update the link with the new one and let FRD resume the download.

I've tried looking in FRD config folder but the information doesn't seem to be stored in an easily editable format.

I've been playing around with ObjectDB Explorer. However, when I try to edit the fileURL field, its type is automatically change from URL to String. Trying to save the DB results in "Attempt to commit a rollback only transaction". Can you tell me the proper way to edit this field? What I did is:

0. Close FRD completely.
1. Run explorer.exe. It automatically open frd.odb
2. Right click on ...DownloadFile and choose Open Tree Window
3. Expand the node I want to change
4. Double click on fileURL and change it
5. Error as above when saving.